The present invention relates to pile up trays or boxes, made of cardboard, intended for the transportation of different types of perishable goods, such as, for example, fruits, vegetables and other like products.
The invention also relates to a method of the manufacture of this type of trays or boxes.
When designing a tray of the type under consideration, a number of conditions that assure a good quality of boxes or trays must be taken into account such that the tray must be resistant to compression, easy to handle, must allow a good presentation of the product to be packed in it, and finally should be recyclable.
Regarding resistance to compression of the tray, the tray must be capable of holding the weight of the product without suffering any deformation of its bottom part. It must hold the stillness while the trays are piled up, it must have a high compression resisting capacity, as a function of the weight to be held, and it must be capable of withstanding vibrations and movements to which the tray is subjected. It must be capable of resisting to conditions of handling, stockage and transportation, specially to the effects of the environmental humidity, which is the case when the humidity in cold storage rooms in which the trays are placed could reach 90%.
Regarding its handling, the tray must offer the possibility of being served in an assembled state, as it is required by small users, or should be dismantable, as it is required by large users that have their own places where it is desirable to use small light machines with greater automation possible.
The tray must also offer excellent conditions for high quality printing and finally, it must avoid such elements as, for example, staples or any other non-recyclable materials.
Basic types of boxes or pile up trays of wood used as raw material or cardboard, are available on the market.
The trays made of wood, although they satisfy the resistance requirement, do not satisfy any of the other requirements previously mentioned, because they are not easy to handle, neither do they offer the possibility of a high quality printing. In addition, wooden trays are not recyclable at a lower cost.
There are many types of well known trays made of cardboard or any other similar material, which are generally formed from a plate properly shaped, with folding lines that define the bottom of the tray, from which elongated wings extend which, when forming the tray, will become the sides of the tray.
This type of trays has some problems during its manufacturing, because cumbersome operations have been needed for assembling the tray and joining the adjacent edges of its sides at the corners of the tray.
Furthermore, the trays of this type are not sufficiently resistant to compression when loaded with the goods and piled up.
This disadvantage occurred because of the difficulty in the folding required for this type of a tray. To do this operation, cardboard has been used, specifically undulating cardboard, that besides offering a low level of resistance is highly absorbent to humidity, which contributes to a quickly damage of the tray.
In many cases, to reinforce the tray, additional pieces are used, particularly placed at the corners. The faces of the tray are reinforced with two flanges bent over the faces of the tray.
This procedure is complicated and increases the cost of production of the tray and, in most cases, the tray does not gain the necessary resistance.
Another problem inherent to conventional trays formed from one piece, is that for providing the graphic printing on the trays, the entire tray must pass through the printing machine even if the printing required is very small or it must be printed in a very small zone of the tray.